Non nucleoside reverse transcriptase inhibitors (NNRTI) bind to an allosteric site on reverse transcriptase and represent an important development in the arsenal of drugs against HIV, particularly HIV-1. International patent application WO 93/03022, discloses thiourea NNRTI which were later denoted “PETT” (phenyl ethyl thiazolyl thiourea) compounds in J Med Chem 39 6 1329-1335 (1995) and J Med Chem 39 21 4261-4274 (1996). International patent application nos. WO99/47501, WO/0039095, WO/0056736, WO00/78315 and WO00/78721 describe thiourea PETT derivatives which have allegedly been optimised against a composite RT binding pocket.
International patent application no WO95/06034 and J Med Chem 42 4150-4160 (1999) disclose urea isosteres of PETT NNRTIs. International patent application no WO99/36406 discloses urea NNRTI compounds with a freestanding cyclopropyl bridge, wherein the phenyl left hand wing bears an obligate 6-hydroxy function and international patent application no WO00/47561 discloses prodrugs of such compounds.
Although the urea and thiourea NNRTI disclosed in the above documents are active against reverse transcriptase, especially that of HIV-1, the nature of the HIV virus with its extreme lack of replicative fidelity and consequent tendency to rapid resistance development prompts a demand for further antiretroviral agents with enhanced antiviral performance against problematic drug escape mutants, notably at the RT 100, 103 and/or 181 positions.
Additionally, modern HIV therapy regimes, denoted HMRT, Highly Active Anti Retroviral Therapy, administer antivirals as combinations of three or more antivirals of various classes, which combinations are administered for prolonged periods, if not for life. HAART requires the patient to follow a complicated dosing schedule with sometimes dozens of tablets per day taken at various times of the day in some cases before and in other cases after the ingestion of food. There is thus a need for antiretroviral preparations allowing greater flexibility in dosing to facilitate patient compliance.